EGSA Automatic Transfer Switch Function 3

Question 1

What type of ATS performs a 'make-before-break' switching sequence?

Accepted Answer

Closed-transition ATS

Answer

A closed-transition ATS briefly parallels both sources during transfer, making the connection to the new source before breaking from the old source to achieve a seamless transfer.

Question 2

Which NFPA 110 Type designation requires the ATS to transfer load within 10 seconds?

Accepted Answer

Type 10

Answer

NFPA 110 Type 10 specifies that the alternate power source must supply power to the load within 10 seconds of normal source failure.

Question 3

When an ATS is described as 'switched neutral,' it means the neutral is:

Accepted Answer

Transferred simultaneously with the phase conductors

Answer

A switched neutral (four-pole) ATS transfers the neutral conductor along with the phase conductors, required for separately derived systems where each source has its own neutral-ground bond.

Question 4

What is the function of a 'load shed' output on an ATS controller?

Accepted Answer

To signal non-critical loads to disconnect when the generator is supplying power

Answer

The load shed output signals load management panels to disconnect non-essential loads, preventing generator overload when critical and non-critical loads share the same emergency distribution system.

Question 5

A 'programmed transition' ATS differs from a standard open-transition ATS because it:

Accepted Answer

Waits a fixed time in neutral to allow motors to de-energize before reconnecting

Answer

A programmed transition ATS adds a fixed neutral dwell time between opening one source and closing the other, reducing voltage transients caused by residual motor flux.

(EGSA) Electrical Generating Systems Association Certified Practice Test

(EGSA) Electrical Generating Systems Association Certified Practice Test

EGSA Automatic Transfer Switch Function 3